HR: 1330h
AN: SM42B-0603    [PDF]
TI: The development of parallel electric fields during substorm growth phases as a result of differential particle mirroring
AU: * Lessard, M R
EM: marc.lessard@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755 United States
AU: Lotko, W
EM: william.lotko@dartmouth.edu
AF: Dartmouth College, Thayer School of Engineering, Hanover, NH 03755 United States
AB: Recent work has shown that the development of an auroral arc during a substorm growth phase is a gradual process where the arc forms within a region of diffuse precipitation and appears to intensify throughout the growth phase. The gradual intensification and stationarity of the arc suggests that the acceleration potential does not result from double-layers or Alfven waves, but perhaps from charge separation. Charge separation resulting from differential mirroring has been studied for decades. During a substorm growth-phase, ions are scattered as a result of increased magnetic field curvature; electron scattering does occur, but may or may not coincide with the evolution of the growth phase. In any case, the scattering mechanisms for ions and electrons are clearly different from each other and so a parallel electric field would result unless each pitch-angle bin is filled with equal numbers of positive and negative particles by chance. The improbability of this situation implies that differential mirroring may play a key role in the development of growth-phase auroral arcs. In this study, specific cases of growth--phase arcs are examined using ground and satellite data and compared with theoretical predictions of parallel fields resulting from differential
DE: 2407 Auroral ionosphere (2704)
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2451 Particle acceleration
DE: 2704 Auroral phenomena (2407)
DE: 2712 Electric fields (2411)
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting